1. Field of the Invention
The invention of this application relates to telephone keypads and more particularly to a method for mapping the inputs generated by the operation of a keypad for a mobile telephone.
2. Brief Description of Related Developments
In several emerging mobile phone markets, there are obstacles in the way of everyday usage created by the large alphabets present in the language, for example Thai and Hindi. Such large alphabets challenge the prevailing systems for entering text into the phone for address books, messaging and other purposes. The prevailing system of multi-tap, based on the Latin alphabet which is comprised of 26 characters, becomes cumbersome when applied to, for example the Thai alphabet of 70 characters.
The keypad is the main user interface for entering text in a mobile phone product. In such devices, there are generally 10 numeric keys that can be used to enter numerical and alphabetic characters. To enter alphabetic characters, a couple of letters are mapped into each key. Some disambiguation technologies are needed to pick the right letter. Multi-tap is one of the most common techniques in disambiguating keystrokes. With this approach, the user presses each key one or more times to specify the input character. For example, in an English input method, key 2 is pressed once for the character A, twice for B, and three times for C. Applying this technique to an alphabet consisting of 70 characters, such as the Thai alphabet, requires that, if all the letters are mapped into the numeric keys, on the average, about 8 letters have to be mapped to each key. Several problems become immediately apparent. First, it is extremely difficult to physically print all the mapped letters on the keys, as the space on the keypad is too limited. To compromise and print a range of characters requires the user to remember the mapping logic. In such a system, it will be difficult for the user to search and enter the right letter, since too many letters are mapped into each key.
One solution in the prior art for this problem is to imprint only letters at breaking points on the physical key. Using English as an example, in an ITU-T keypad English input, “a b c” is mapped to key 2. “d e f” is mapped to key 3, and so on. So “a” and “c”, “d” and “f” are the breaking points in the alphabet. In the solution, the labels like “a-c”, “d-f” are printed on the numeric keys. If only breaking letters are shown on the keys using an extensive alphabet, the user has to memorize all the letters that fall between two breaking points. This is a significant burden when an alphabet, such as Thai or Hindi is applied. Users have to figure out how many presses are needed to find the right letter.
Another prior art solution is to support only partial alphabet by multi-tap input. For example, some Thai inputs only support multi-tap to input consonants. All the other vowels, diacritics, tone marks, etc. are shown in one grid for user to select. Just as special character input in Chinese, all the special characters are shown in the grid, user can navigate and select by navi keys.
This input method, however, is not consistent for different letter groups. The user has to use different logic and process to enter different letter groups. Multi-tapping is used to enter consonants and grid navigation is used to input vowels and tone marks. Grid selection is time consuming and prone to errors.
It is an object of this invention to provide a method of mapping characters to a mobile telephone keypad that is consistent in all alphabet letters, so that the user can use the same logic and sequence to input all the alphabet items, including consonants, vowels, diacritics, tone marks and other common items.
It is another object of this invention, to limit the need for a user to remember key mapping details when they search for the right letter, by providing visual indications to assist in the selection of the right key and the right number of times a key needs to be pressed for the desired character.
It is another object of this invention to avoid the need for a user to move their focus between physical keyboard and display, by providing enough information on a display screen and mapping non-consonant items in a user-friendly way to enable a user to find the desired non-consonant items easily.